Lumber stick construction which employs 2.times. dimensional structural lumber members and nails is how most houses are constructed. This handcrafted stick built approach is slow and manpower intensive requiring many hours of field work, requires a large supply of a limited natural resource, typically incorporates many thermal bridges in combination with gaps in insulation and thus is not particularly energy efficient, and affords a limited number of structural shapes. An alternative approach employs steel studs. This approach also suffers from limitations in that the steel studs are difficult to work with and are good thermal conductors of heat through walls and roofs.
Another approach gaining increasing acceptance involves the use of Structural Insulated Panels (SIPs). SIP construction typically employs two rigid faces on either side of a light insulating foam core. High strength bonding of the outer facings to the inner core forms a structural I-beam in the form of flat panels which are typically joined together by lumber and nails. The outer, opposed panel faces are generally formed from conventional building materials such as gypsum or cementous composites, plywood, oriented strand board (OSB), drywall, or other rigid construction boards from 1/4" to 3/4" thick. Several factors have impeded wide-spread acceptance of SIPs in building construction. For example, the use of SIPs requires a great deal of pre-planning for efficient field erection because these panels are not easily field-cut without the use of special tools. Manufacturing the panels involves 4-5 times the amount of time cutting and sizing the panels in the shop than required in laminating the panels. This increased in-shop preparation of the panels also requires additional in-house designers. In addition, these panels are generally heavy, weighing much more than conventional wallboard panels, and frequently require the use of special handling equipment such as cranes. Because SIPs are difficult to modify in the field, more precise planning and building techniques are required than the stick built approach of simply working out of a wood pile of 2.times. dimensional structural lumber members. Finally, current double-faced structural insulated panels are typically 5" thick when installed with drywall. This is wider than typical stick framing of 41/2" thickness and requires special door and window jamb sizes. Current structural insulated panels are thus incompatible with the conventional 2.times. structural member system of construction in general use today. For these reasons, contractors have not accepted SIPs as a basic structural member in building construction on a widespread scale.
The present invention addresses the aforementioned limitations of the prior art by providing a lightweight, high strength, insulated panel which is easily fabricated, modified and installed in structures built with 2.times. stick construction.